Upgrade from Sitefinity CMS 9.1 and above
If your project is running on Sitefinity CMS 9.1 and above, to upgrade it, perform the following:
    - Backup your project and its database.
 
    - Set the target framework version of your project to .NET Framework 4.7.2.
    Perform the following:
    
        - Open your project in Visual Studio.
 
        - In the context menu of SitefinityWebApp, click Properties.
 
        - On Application tab, in Target framework dropdown box, select .NET Framework 4.7.2
 
        - Save the changes to your project
 
    
     
    - Reinstall all packages:
    
        - In Visual Studio, navigate to Tools » NuGet Package Manager » Package Manager Console.
 
        - Execute the following command: Update-Package -Reinstall
        
 NOTE: You do this, because the changing the target framework requires re-installation of all packages. After you have removed all Sitefinity CMS related packages in Step 2, you perform this step to re-install all other packages that you may have installed on your system.
         
    
     
    - In the Package Manager Console, install 
Telerik.Sitefinity.All 12.1.7100.0 using the following command:
     Install-Package Telerik.Sitefinity.All –Version 12.1.7100.0 
     NOTE: The BCL dependency used by Sitefinity CMS to integrate Azure search in previous versions is also removed. As a result, you can safely remove the Tools folder under the root of your SitefinityWebApp project. 
     
    - In the Package Manager Console, uninstall the following packages and delete the respective assemblies from the project's 
bin folder:
    
        Telerik.Sitefinity.Thunder 
        Telerik.Sitefinity.DropboxLibraries 
        Telerik.Sitefinity.MobileAppBuilder 
        Telerik.Sitefinity.DAM 
        Telerik.Sitefinity.EverliveConnector 
    
     
    - Build your solution.